The relationship between beta-ureidopropionase deficiency due to UPB1 variants and human phenotypes is uncertain.

BACKGROUND: Beta-ureidopropionase deficiency, caused by variants in UPB1, has been reported in association with various neurodevelopmental phenotypes including intellectual disability, seizures and autism. AIM: We aimed to reassess the relationship between variants in UPB1 and a clinical phenotype. METHODS: Literature review, calculation of carrier frequencies from population databases, long-term follow-up of a previously published case and reporting of additional cases. RESULTS: Fifty-three published cases were identified, and two additional cases are reported here. Of these, 14 were asymptomatic and four had transient neurological features; clinical features in the remainder were variable and included non-neurological presentations. Several of the variants previously reported as pathogenic are present in population databases at frequencies higher than expected for a rare condition. In particular, the variant most frequently reported as pathogenic, p.Arg326Gln, is very common among East Asians, with a carrier frequency of 1 in 19 and 1 in 907 being homozygous for the variant in gnomAD v2.1.1. CONCLUSION: Pending the availability of further evidence, UPB1 should be considered a 'gene of uncertain clinical significance'. Caution should be used in ascribing clinical significance to biochemical features of beta-ureidopropionase deficiency and/or UPB1 variants in patients with neurodevelopmental phenotypes. UPB1 is not currently suitable for inclusion in gene panels for reproductive genetic carrier screening. SYNOPSIS: The relationship between beta-ureidopropionase deficiency due to UPB1 variants and clinical phenotypes is uncertain.

Variants of HCMV UL18 Sequenced Directly from Clinical Specimens Associate with Antibody and T-Cell Responses to HCMV.

Around 80% of adults worldwide carry human cytomegaloviris (HCMV). The HCMV gene UL18 is a homolog of HLA class I genes and encodes a protein with high affinity for the NK and T-cell cytotoxicity inhibitor LIR-1. UL18 was deep sequenced from blood, saliva or urine from Indonesian people with HIV (PWH) (n = 28), Australian renal transplant recipients (RTR) (n = 21), healthy adults (n = 7) and neonates (n = 4). 95% of samples contained more than one variant of HCMV UL18, as defined by carriage of nonsynonymous variations. When aligned with immunological markers of the host's burden of HCMV, the S318N variation associated with high levels of antibody reactive with HCMV lysate in PWH over 12 months on antiretroviral therapy. The A107T variation associated with HCMV antibody levels and inflammatory biomarkers in PWH at early timepoints. Variants D32G, D248N, V250A and E252D aligned with elevated HCMV antibody levels in RTR, while M191K, E196Q and F165L were associated with HCMV-reactive T-cells and proportions of Vδ2- γδ T-cells-populations linked with high burdens of HCMV. We conclude that UL18 is a highly variable gene, where variation may alter the persistent burden of HCMV and/or the host response to that burden.

Sequencing of the Viral UL111a Gene Directly from Clinical Specimens Reveals Variants of HCMV-Encoded IL-10 That Are Associated with Altered Immune Responses to HCMV.

Human cytomegalovirus (HCMV) is a beta-herpesvirus carried by ~80% of adults worldwide. Acute infections are often asymptomatic in healthy individuals but generate diverse syndromes in neonates, renal transplant recipients (RTR), and people with HIV (PWH). The HCMV gene UL111a encodes a homolog of human interleukin-10 (IL-10) that interacts with the human IL-10 receptor. Deep sequencing technologies were used to sequence UL111a directly from 59 clinical samples from Indonesian PWH and Australian RTR, healthy adults, and neonates. Overall, 93% of samples contained more than one variant of HCMV, as defined by at least one nonsynonymous variation. Carriage of these variants differed between neonates and adults, Australians and Indonesians, and between saliva and blood leukocytes. The variant alleles of N41D and S71Y occurred together in Australian RTR and were associated with higher T-cell responses to HCMV pp65. The variant P122S was associated with lower levels of antibodies reactive with a lysate of HCMV-infected fibroblasts. L174F was associated with increased levels of antibodies reactive with HCMV lysate, immediate-early 1 (IE-1), and glycoprotein B (gB) in Australian RTR and Indonesians PWH, suggesting a higher viral burden. We conclude that variants of UL111a are common in all populations and may influence systemic responses to HCMV.

Platelets in myeloproliferative neoplasms have a distinct transcript signature in the presence of marrow fibrosis.

Marrow fibrosis is a significant complication of myeloproliferative neoplasms (MPN) that affects up to 20% of patients and is associated with a poor prognosis. The pathological processes that lead to fibrotic progression are not well understood, but megakaryocytes have been implicated in the process. The aim of this study was to determine whether platelets, derived from megakaryocytes, have transcriptomic alterations associated with fibrosis. Platelets from MPN patients with and without fibrosis and non-malignant control individuals were assessed using next generation sequencing. Results from the initial training cohort showed discrete changes in platelet transcripts in the presence of marrow fibrosis. We identified more than 1000 differentially expressed transcripts from which a putative 3-gene fibrotic platelet signature (CCND1, H2AX [previously termed H2AFX] and CEP55) could be identified. This fibrosis-associated signature was assessed blinded on platelets from an independent test MPN patient cohort. The 3-gene signature was able to discriminate between patients with and without marrow fibrosis with a positive predictive value of 71% (93% specificity, 71% sensitivity). This demonstrates that assessment of dysregulated transcripts in platelets may be a useful monitoring tool in MPN to identify progression to marrow fibrosis. Further, sequential monitoring could have clinical applications for early prediction of progression to fibrosis.

Mutations of GPR126 are responsible for severe arthrogryposis multiplex congenita.

Arthrogryposis multiplex congenita is defined by the presence of contractures across two or more major joints and results from reduced or absent fetal movement. Here, we present three consanguineous families affected by lethal arthrogryposis multiplex congenita. By whole-exome or targeted exome sequencing, it was shown that the probands each harbored a different homozygous mutation (one missense, one nonsense, and one frameshift mutation) in GPR126. GPR126 encodes G-protein-coupled receptor 126, which has been shown to be essential for myelination of axons in the peripheral nervous system in fish and mice. A previous study reported that Gpr126(-/-) mice have a lethal arthrogryposis phenotype. We have shown that the peripheral nerves in affected individuals from one family lack myelin basic protein, suggesting that this disease in affected individuals is due to defective myelination of the peripheral axons during fetal development. Previous work has suggested that autoproteolytic cleavage is important for activating GPR126 signaling, and our biochemical assays indicated that the missense substitution (p.Val769Glu [c.2306T>A]) impairs autoproteolytic cleavage of GPR126. Our data indicate that GPR126 is critical for myelination of peripheral nerves in humans. This study adds to the literature implicating defective axoglial function as a key cause of severe arthrogryposis multiplex congenita and suggests that GPR126 mutations should be investigated in individuals affected by this disorder.

Megakaryocytes in Myeloproliferative Neoplasms Have Unique Somatic Mutations.

Myeloproliferative neoplasms (MPNs) are a group of related clonal hemopoietic stem cell disorders associated with hyperproliferation of myeloid cells. They are driven by mutations in the hemopoietic stem cell, most notably JAK2V617F, CALR, and MPL. Clinically, they have the propensity to progress to myelofibrosis and transform to acute myeloid leukemia. Megakaryocytic hyperplasia with abnormal features are characteristic, and it is thought that these cells stimulate and drive fibrotic progression. The biological defects underpinning this remain to be explained. In this study we examined the megakaryocyte genome in 12 patients with MPNs to determine whether there are somatic variants and whether there is any association with marrow fibrosis. We performed targeted next-generation sequencing for 120 genes associated with myeloid neoplasms on megakaryocytes isolated from aspirated bone marrow. Ten of the 12 patients had genomic defects in megakaryocytes that were not present in nonmegakaryocytic hemopoietic marrow cells from the same patient. The greatest allelic burden was in patients with increased reticulin deposition. The megakaryocyte-unique mutations were predominantly in genes that regulate chromatin remodeling, chromosome alignment, and stability. These findings show that genomic abnormalities are present in megakaryocytes in MPNs and that these appear to be associated with progression to bone marrow fibrosis.

SPEG interacts with myotubularin, and its deficiency causes centronuclear myopathy with dilated cardiomyopathy.

Centronuclear myopathies (CNMs) are characterized by muscle weakness and increased numbers of central nuclei within myofibers. X-linked myotubular myopathy, the most common severe form of CNM, is caused by mutations in MTM1, encoding myotubularin (MTM1), a lipid phosphatase. To increase our understanding of MTM1 function, we conducted a yeast two-hybrid screen to identify MTM1-interacting proteins. Striated muscle preferentially expressed protein kinase (SPEG), the product of SPEG complex locus (SPEG), was identified as an MTM1-interacting protein, confirmed by immunoprecipitation and immunofluorescence studies. SPEG knockout has been previously associated with severe dilated cardiomyopathy in a mouse model. Using whole-exome sequencing, we identified three unrelated CNM-affected probands, including two with documented dilated cardiomyopathy, carrying homozygous or compound-heterozygous SPEG mutations. SPEG was markedly reduced or absent in two individuals whose muscle was available for immunofluorescence and immunoblot studies. Examination of muscle samples from Speg-knockout mice revealed an increased frequency of central nuclei, as seen in human subjects. SPEG localizes in a double line, flanking desmin over the Z lines, and is apparently in alignment with the terminal cisternae of the sarcoplasmic reticulum. Examination of human and murine MTM1-deficient muscles revealed similar abnormalities in staining patterns for both desmin and SPEG. Our results suggest that mutations in SPEG, encoding SPEG, cause a CNM phenotype as a result of its interaction with MTM1. SPEG is present in cardiac muscle, where it plays a critical role; therefore, individuals with SPEG mutations additionally present with dilated cardiomyopathy.

Towards a Universal Molecular Microbiological Test.

The standard paradigm for microbiological testing is dependent on the presentation of a patient to a clinician. Tests are then requested based on differential diagnoses using the patient's symptoms as a guide. The era of high-throughput genomic methods has the potential to replace this model for the first time with what could be referred to as "hypothesis-free testing." This approach utilizes one of a variety of methodologies to obtain a sequence from potentially any nucleic acid in a clinical sample, without prior knowledge of its content. We discuss the advantages of such an approach and the challenges in making this a reality.

Whole exome sequencing of an asbestos-induced wild-type murine model of malignant mesothelioma.

BACKGROUND: Malignant mesothelioma (MM) is an aggressive cancer of the pleural and peritoneal cavities caused by exposure to asbestos. Asbestos-induced mesotheliomas in wild-type mice have been used extensively as a preclinical model because they are phenotypically identical to their human counterpart. However, it is not known if the genetic lesions in these mice tumours are similar to in the human disease, a prerequisite for any new preclinical studies that target genetic abnormalities. METHODS: We performed whole exome sequencing of fifteen asbestos-induced murine MM tumour cell lines from BALB/c, CBA and C57BL/6 mouse strains and compared the somatic mutations and copy number variations with those recurrently reported in human MM. We then catalogued and characterised the mutational landscape of the wild-type murine MM tumours. Quantitative RT-PCR was used to interrogate the expression of key MM genes of interest in the mRNA. RESULTS: Consistent with human MM tumours, we identified homozygous loss of the tumour suppressor Cdkn2a in 14/15 tumours. One tumour retained the first exon of both of the p16INK4a and p19ARF isoforms though this tumour also contained genetic amplification of Myc resulting in increased expression of the c-Myc proto-oncogene in the mRNA. There were no chromosomal losses in either the Bap1 or Nf2 regions. One tumour harbored homozygous loss of Trp53 in the DNA. Mutation rates were similar in tumours generated in the CBA and C57BL/6 strains when compared to human MM. Interestingly, all BALB/c tumour lines displayed high mutational loads, consistent with the known mutator phenotype of the host strain. The Wnt, MAPK and Jak-STAT signaling pathways were found to be the most commonly affected biological pathways. Mutations and copy number deletions also occurred in the Hedgehog and Hippo pathways. CONCLUSIONS: These data suggest that in the wild-type murine model asbestos causes mesotheliomas in a similar way to in human MM. This further supports the notion that the murine model of MM represents a genuine homologue of the human disease, something uncommon in cancer, and is thus a valuable tool to provide insight into MM tumour development and to aide the search for novel therapeutic strategies.

Mutations in CYC1, encoding cytochrome c1 subunit of respiratory chain complex III, cause insulin-responsive hyperglycemia.

Many individuals with abnormalities of mitochondrial respiratory chain complex III remain genetically undefined. Here, we report mutations (c.288G>T [p.Trp96Cys] and c.643C>T [p.Leu215Phe]) in CYC1, encoding the cytochrome c1 subunit of complex III, in two unrelated children presenting with recurrent episodes of ketoacidosis and insulin-responsive hyperglycemia. Cytochrome c1, the heme-containing component of complex III, mediates the transfer of electrons from the Rieske iron-sulfur protein to cytochrome c. Cytochrome c1 is present at reduced levels in the skeletal muscle and skin fibroblasts of affected individuals. Moreover, studies on yeast mutants and affected individuals' fibroblasts have shown that exogenous expression of wild-type CYC1 rescues complex III activity, demonstrating the deleterious effect of each mutation on cytochrome c1 stability and complex III activity.

Identification of KLHL41 Mutations Implicates BTB-Kelch-Mediated Ubiquitination as an Alternate Pathway to Myofibrillar Disruption in Nemaline Myopathy.

Nemaline myopathy (NM) is a rare congenital muscle disorder primarily affecting skeletal muscles that results in neonatal death in severe cases as a result of associated respiratory insufficiency. NM is thought to be a disease of sarcomeric thin filaments as six of eight known genes whose mutation can cause NM encode components of that structure, however, recent discoveries of mutations in non-thin filament genes has called this model in question. We performed whole-exome sequencing and have identified recessive small deletions and missense changes in the Kelch-like family member 41 gene (KLHL41) in four individuals from unrelated NM families. Sanger sequencing of 116 unrelated individuals with NM identified compound heterozygous changes in KLHL41 in a fifth family. Mutations in KLHL41 showed a clear phenotype-genotype correlation: Frameshift mutations resulted in severe phenotypes with neonatal death, whereas missense changes resulted in impaired motor function with survival into late childhood and/or early adulthood. Functional studies in zebrafish showed that loss of Klhl41 results in highly diminished motor function and myofibrillar disorganization, with nemaline body formation, the pathological hallmark of NM. These studies expand the genetic heterogeneity of NM and implicate a critical role of BTB-Kelch family members in maintenance of sarcomeric integrity in NM.

Polymorphisms in CAMKK2 may predict sensory neuropathy in African HIV patients.

HIV-associated sensory neuropathy (HIV-SN) is the most common neurological condition associated with HIV. HIV-SN has characteristics of an inflammatory pathology caused by the virus itself and/or by antiretroviral treatment (ART). Here, we assess the impact of single-nucleotide polymorphisms (SNPs) in a cluster of three genes that affect inflammation and neuronal repair: P2X7R, P2X4R and CAMKK2. HIV-SN status was assessed using the Brief Peripheral Neuropathy Screening tool, with SN defined by bilateral symptoms and signs. Forty-five SNPs in P2X7R, P2X4R and CAMKK2 were genotyped using TaqMan fluorescent probes, in DNA samples from 153 HIV(+) black Southern African patients exposed to stavudine. Haplotypes were derived using the fastPHASE algorithm, and SNP genotypes and haplotypes associated with HIV-SN were identified. Optimal logistic regression models included demographics (age and height), with SNPs (model p < 0.0001; R (2) = 0.19) or haplotypes (model p < 0.0001; R (2) = 0.18, n = 137 excluding patients carrying CAMKK2 haplotypes perfectly associated with SN). Overall, CAMKK2 exhibited the strongest associations with HIV-SN, with two SNPs and six haplotypes predicting SN status in black Southern Africans. This gene warrants further study.

Novel CHKB mutation expands the megaconial muscular dystrophy phenotype.

INTRODUCTION: Mutations in the choline kinase beta (CHKB) gene are associated with a congenital muscular dystrophy with giant mitochondria at the periphery of muscle fibers. METHODS: We describe a patient of Italian origin in whom whole-exome sequencing revealed a novel homozygous nonsense mutation, c.648C>A, p.(Tyr216*), in exon 5 of CHKB. RESULTS: The patient presented with limb-girdle weakness and hypotonia from birth with mental retardation, and had sudden and transient deteriorations of muscle strength with acute intercurrent illnesses. Previously undescribed sarcolemmal overexpression of utrophin was noted in the muscle biopsy. CONCLUSIONS: Pathological features broaden the description of the entity and provide new insight in the pathogenic mechanisms. This case highlights the usefulness of next-generation sequencing in the diagnosis of rare and incompletely understood conditions.

Do variations in the HLA-E ligand encoded by UL40 distinguish individuals susceptible to HCMV disease?

Human cytomegalovirus (HCMV) is carried lifelong by ∼80 % of adults worldwide, generating distinct disease syndromes in transplant recipients, people with HIV (PWH) and neonates. Amino acids 15-23 encoded by the HCMV gene UL40 match positions 3-11 of HLA-A and HLA-C, and constitute a "signal peptide" able to stabilise cell surface HLA-E as a restriction element and a ligand of NKG2A and NKG2C. We present next generation sequencing of UL40 amplified from 15 Australian renal transplant recipients (RTR), six healthy adults and four neonates, and 21 Indonesian PWH. We found no groupwise associations between the presence of multiple sequences and HCMV burden (highest in PWH) or HCMV-associated symptoms in neonates. Homology between UL40 and corresponding HLA-C and HLA-A peptides in 11 RTR revealed perfect matches with HLA-C in three individuals, all carrying HCMV encoding only VMAPRTLIL - a peptide previously associated with viremia. However indices of the burden of HCMV did not segregate in our cohort.

The Australian Reproductive Genetic Carrier Screening Project (Mackenzie's Mission): Design and Implementation.

Reproductive genetic carrier screening (RGCS) provides people with information about their chance of having children with autosomal recessive or X-linked genetic conditions, enabling informed reproductive decision-making. RGCS is recommended to be offered to all couples during preconception or in early pregnancy. However, cost and a lack of awareness may prevent access. To address this, the Australian Government funded Mackenzie's Mission­the Australian Reproductive Genetic Carrier Screening Project. Mackenzie's Mission aims to assess the acceptability and feasibility of an easily accessible RGCS program, provided free of charge to the participant. In study Phase 1, implementation needs were mapped, and key study elements were developed. In Phase 2, RGCS is being offered by healthcare providers educated by the study team. Reproductive couples who provide consent are screened for over 1200 genes associated with >750 serious, childhood-onset genetic conditions. Those with an increased chance result are provided comprehensive genetic counseling support. Reproductive couples, recruiting healthcare providers, and study team members are also invited to complete surveys and/or interviews. In Phase 3, a mixed-methods analysis will be undertaken to assess the program outcomes, psychosocial implications and implementation considerations alongside an ongoing bioethical analysis and a health economic evaluation. Findings will inform the implementation of an ethically robust RGCS program.

Longitudinal Survey of Fecal Microbiota in Healthy Dogs Administered a Commercial Probiotic.

The aim of this longitudinal microbiome study was to investigate the effects of a commercially available veterinary synbiotic product (Blackmore's® Paw DigestiCare 60™) on the fecal microbiome of healthy dogs using 16S rRNA gene microbial profiling. Fifteen healthy, privately-owned dogs participated in a 2-week trial administration of the product. Fecal samples were collected at different time points, including baseline (prior to treatment), during administration and after discontinuation of product. Large intra- and inter-individual variation was observed throughout the study, but microbiome composition at higher phylogenetic levels, alpha and beta diversity were not significantly altered after 2 weeks of probiotic administration, suggesting an absence of probiotic impact on microbial diversity. Administration of the synbiotic preparation did, however, result in transient increases in probiotic species from Enterococacceae and Streptococacceae families as well as an increase in Fusobacteria; with the fecal microbiota partially reverting to its baseline state 3-weeks after cessation of probiotic administration.

Sequencing Directly from Clinical Specimens Reveals Genetic Variations in HCMV-Encoded Chemokine Receptor US28 That May Influence Antibody Levels and Interactions with Human Chemokines.

Human cytomegalovirus (HCMV) is a beta-herpesvirus carried by ∼80% of the world's population. Acute infections are asymptomatic in healthy individuals but generate diverse syndromes in neonates, solid organ transplant recipients, and HIV-infected individuals. The HCMV gene US28 encodes a homolog of a human chemokine receptor that is able to bind several chemokines and HIV gp120. Deep sequencing technologies were used to sequence US28 directly from 60 clinical samples from Indonesian HIV patients and Australian renal transplant recipients, healthy adults, and neonates. Molecular modeling approaches were used to predict whether nine nonsynonymous mutations in US28 may alter protein binding to a panel of six chemokines and two variants of HIV gp120. Ninety-two percent of samples contained more than one variant of HCMV, as defined by at least one nonsynonymous mutation. Carriage of these variants differed between neonates and adults, Australian and Indonesian samples, and saliva samples and blood leukocytes. Two nonsynonymous mutations (N170D and R267K) were associated with increased levels of immediate early protein 1 (IE-1) and glycoprotein B (gB) HCMV-reactive antibodies, suggesting a higher viral burden. Seven of the nine mutations were predicted to alter binding of at least one ligand. Overall, HCMV variants are common in all populations and have the potential to affect US28 interactions with human chemokines and/or gp120 and alter responses to the virus. The findings relied on deep sequencing technologies applied directly to clinical samples, so the variants exist in vivo. IMPORTANCE Human cytomegalovirus (HCMV) is a common viral pathogen of solid organ transplant recipients, neonates, and HIV-infected individuals. HCMV encodes homologs of several host genes with the potential to influence viral persistence and/or pathogenesis. Here, we present deep sequencing of an HCMV chemokine receptor homolog, US28, acquired directly from clinical specimens. Carriage of these variants differed between patient groups and was associated with different levels of circulating HCMV-reactive antibodies. These features are consistent with a role for US28 in HCMV persistence and pathogenesis. This was supported by in silico analyses of the variant sequences demonstrating altered ligand-binding profiles. The data delineate a novel approach to understanding the pathogenesis of HCMV and may impact the development of an effective vaccine.

Low-Pass Whole-Genome Sequencing as a Method of Determining Copy Number Variations in Uveal Melanoma Tissue Samples.

Analysis of specific somatic copy number alterations (SCNAs) using multiplex ligation-dependent probe amplification (MLPA) is used routinely as a prognostic test for uveal melanoma (UM). This technique requires relatively large amounts of input DNA, unattainable from many small fine-needle aspirate biopsy specimens. Herein, we compared the use of MLPA with whole-genome amplification (WGA) combined with low-pass whole-genome sequencing (LP-WGS) for detection of SCNA profiles in UM biopsy specimens. DNA was extracted from 21 formalin-fixed, paraffin-embedded UM samples and SCNAs were assessed using MLPA and WGA followed by LP-WGS. Cohen's κ was used to assess the concordance of copy number calls of each individual chromosome arm for each patient. MLPA and WGA/LP-WGS detection of SCNAs in chromosomes 1p, 3, 6, and 8 were compared and found to be highly concordant with a Cohen's κ of 0.856 (bias-corrected and accelerated 95% CI, 0.770-0.934). Only 13 of 147 (8.8%) chromosomal arms investigated resulted in discordant calls, predominantly SCNAs detected by WGA/LP-WGS but not MLPA. These results indicate that LP-WGS might be a suitable alternative or adjunct to MLPA for the detection of SCNAs associated with prognosis of UM, for cases with limiting tissue or DNA yields.

Identification of a CD8+ T-cell response to a predicted neoantigen in malignant mesothelioma.

Neoantigens present unique and specific targets for personalized cancer immunotherapy strategies. Given the low mutational burden yet immunotherapy responsiveness of malignant mesothelioma (MM) when compared to other carcinogen-induced malignancies, identifying candidate neoantigens and T cells that recognize them has been a challenge. We used pleural effusions to gain access to MM tumor cells as well as immune cells in order to characterize the tumor-immune interface in MM. We characterized the landscape of potential neoantigens from SNVs identified in 27 MM patients and performed whole transcriptome sequencing of cell populations from 18 patient-matched pleural effusions. IFNγ ELISpot was performed to detect a CD8+ T cell responses to predicted neoantigens in one patient. We detected a median of 68 (range 7-258) predicted neoantigens across the samples. Wild-type non-binding to mutant binding predicted neoantigens increased risk of death in a model adjusting for age, sex, smoking status, histology and treatment (HR: 33.22, CI: 2.55-433.02, p = .007). Gene expression analysis indicated a dynamic immune environment within the pleural effusions. TCR clonotypes increased with predicted neoantigen burden. A strong activated CD8+ T-cell response was identified for a predicted neoantigen produced by a spontaneous mutation in the ROBO3 gene. Despite the challenges associated with the identification of bonafide neoantigens, there is growing evidence that these molecular changes can provide an actionable target for personalized therapeutics in difficult to treat cancers. Our findings support the existence of candidate neoantigens in MM despite the low mutation burden of the tumor, and may present improved treatment opportunities for patients.

Arthritogenic Alphavirus Vaccines: Serogrouping Versus Cross-Protection in Mouse Models.

Chikungunya virus (CHIKV), Ross River virus (RRV), o'nyong nyong virus (ONNV), Mayaro virus (MAYV) and Getah virus (GETV) represent arthritogenic alphaviruses belonging to the Semliki Forest virus antigenic complex. Antibodies raised against one of these viruses can cross-react with other serogroup members, suggesting that, for instance, a CHIKV vaccine (deemed commercially viable) might provide cross-protection against antigenically related alphaviruses. Herein we use human alphavirus isolates (including a new human RRV isolate) and wild-type mice to explore whether infection with one virus leads to cross-protection against viremia after challenge with other members of the antigenic complex. Persistently infected Rag1-/- mice were also used to assess the cross-protective capacity of convalescent CHIKV serum. We also assessed the ability of a recombinant poxvirus-based CHIKV vaccine and a commercially available formalin-fixed, whole-virus GETV vaccine to induce cross-protective responses. Although cross-protection and/or cross-reactivity were clearly evident, they were not universal and were often suboptimal. Even for the more closely related viruses (e.g., CHIKV and ONNV, or RRV and GETV), vaccine-mediated neutralization and/or protection against the intended homologous target was significantly more effective than cross-neutralization and/or cross-protection against the heterologous virus. Effective vaccine-mediated cross-protection would thus likely require a higher dose and/or more vaccinations, which is likely to be unattractive to regulators and vaccine manufacturers.